Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test.

Nanodiamonds functionalized with different organic moieties carrying terminal amino groups have been synthesized. These include conjugates generated by Diels-Alder reactions of ortho-quinodimethanes formed in situ from pyrazine and 5,6-dihydrocyclobuta[d]pyrimidine derivatives. For the quantification of primary amino groups a modified photometric assay based on the Kaiser test has been developed and validated for different types of aminated nanodiamond. The results correspond well to values obtained by thermogravimetry. The method represents an alternative wet-chemical quantification method in cases where other techniques like elemental analysis fail due to unfavourable combustion behaviour of the analyte or other impediments.

Functionalization of bone implants with nanodiamond particles and angiopoietin-1 to improve vascularization and bone regeneration.

One of the major challenges in bone tissue engineering is adequate vascularization within bone substituents for nutrients and oxygen supply. In this study, the production and results of a new, highly functional bone construct consisting of a commercial three-dimensional ß-tricalcium phosphate scaffold (ß-TCP, ChronOS®) and hydrophilic, functionalized nanodiamond (ND) particles are reported. A 30-fold increase in the active surface area of the ChronOS + ND scaffold was achieved after modification with ND. In addition, immobilization of angiopoietin-1 (Ang-1) via physisorption within the ß-TCP + ND scaffold retained the bioactivity of the growth factor. Homogeneous distribution of the ND and Ang-1 within the core of the three-dimensional scaffold was confirmed using ND covalently labelled with Oregon Green. The biological responses of the ß-TCP + ND scaffold with and without Ang-1 were studied in a sheep calvaria critical size defect model showing that the ß-TCP + ND scaffold improved the blood vessel ingrowth and the ß-TCP + ND + ND + Ang-1 scaffold further promoted vascularization and new bone formation. The results demonstrate that the modification of scaffolds with tailored diamond nanoparticles is a valuable method for improving the characteristics of bone implants and enables new approaches in bone tissue engineering.

CuAAC click functionalization of azide-modified nanodiamond with a photoactivatable CO-releasing molecule (PhotoCORM) based on [Mn(CO)3(tpm)]+.

The copper-catalyzed 1,3-dipolar azide-alkyne cycloaddition (CuAAC) was used for the first time to attach a biologically active carbon monoxide delivery agent to modified nanodiamond (ND) as a highly biocompatible carrier. The [Mn(CO)(3)(tpm)](+) photoactivatable CO-releasing molecule (PhotoCORM) on the surface retained the carbon monoxide release properties of the parent compound as shown with the myoglobin assay.

Deagglomeration and surface modification of thermally annealed nanoscale diamond.

Thermally annealed nanodiamond has been functionalized by C-C coupling of the partially graphitized diamond surface using aryl diazonium salts. Depending on the terminal functional groups, the modified bucky diamond nanoparticles show good solubility (up to 0.63mgmL(-1)) in different solvents. The agglomerate size of the originally strongly bound detonation diamond (>0.5µm) is substantially reduced to ∼20-50nm by this chemical procedure and without using mechanical techniques such as strong ultrasound or milling. Arylation with functionalized aryl diazonium salts carrying COOH, SO(3)H, NO(2) or bromoethyl groups opens the way for further covalent grafting of organic structures. Arylation with Ar-COOH or Ar-SO(3)H leads to the formation of stable colloidal solutions in water and physiological media (i.e. PBS buffer), an important prerequisite for biomedical applications.